Piston construction



Dec. 12, 1944. s S HNELL 2,364,823-

' PISTON CONSTRUCTION Filed Sept. 7, 1942 2 Sheets-Sheet l T 1/5 Sam/ELL,

Dec.'1 2, 1944.

's. SCHNELL PISTON CONSTRUCTION Filed Sept. 7, 1942 2 Sheets-Sheet 2 Patented Dec. 12, 1944 zse sza Steve Schn'eli, Kirkwood, Ma; assignorto-Wag Her-Electric" Gorp'oration, St. Louis, Mo., a corporatioir of Delaware plication September 7, imazs eriaiivoz45%1615? on; the .othenside withoutimovementtof the'isealing means for2 the piston; relatively to. :the:.=wall engaged .thereby:.

Another-object of :my' inventionx-isgtoso emrploy a;=7diaphragmta apart of:.a fioating?partition be tweentwo fluids under pressurelthat .it'w'ill func'ev tion as. a 'seal :between Atheafiuids and also asaa flexible" member to" permit limited changes in pressures" of? the. fluids without .lmovem'ent of its sealing portion relatively tonthewall ofthe' mem berx in..which the seal is mounted and" also: so mounted thatzduring large variations iii-pres.- surethe: diaphragm will be movedbodilyto maintain;the fluid pressuresequal.

Still another object of my-invention is t'o produceaniimprovedyieldable device having relatively movable telescoping cylinders and containinga non-compressible fluid and a compressibletfiuid unde1=='pressure with 'axmovable' piston construction as -a partition forthefiuids.

Other' objectsof 'my-inventionwill become-apparent: from 1 the following description takem in connection with the accompanying drawings in which Figur -11s a-view of I an improved yieldable 'device'embodying my invention; said device being used as a strutbetween an vehicle frame and 'a wheel thereofj Figures 2'-and-3-'are en'- larged longitudinal sectional views of the upper and lower portions of the yieldable device showing details thereof; Figure-dis an enlarged sectional View of my improved piston construction; and Figure is a sectional view-taken ontheline 5"-5' of Figure 2.

Referring to the drawings in detail and first to- Figure 1, I haveshow'rr my improved yieldable vehicle there is"interposedtlie devie or'strut'fl;

the. connection being. made 'l' y Halli andsocket commonest andJL i v 'c :yieldabl device .or 'strut' l'iis-s'hownin'fdfi taiiiinfigures 2;,3;4;;and.i5; .rerrencezw wmch is now mja'de. Thestrutiis cOmpOsedbftWdteIe at its-upper vend by. a cap I-Bfproviddi'with" aball ill L formingepart of; tfie-ball' and socket cornice-'- tion .L and cylinder 9" beirigclsed at'lits ower end by a calp l2provided' with a'socket I 3361* re ceiving, .balll4" of.thezbalf'andfsocket' connection 6; w, said ball being, \hel'dfin socketf by a 'plate ISL The externalidiameter ofi cylinder 8is somewhatless than .tfie internalfdianieter of 'jeyli'nder fi thus producing a chamberlfi .betweenith'e walls ofithes twocylinders; The lower end 'oficylinder .8; which is. re'ceived in.-cylindr Q'LQarries a sleeve I1 which;has-such.an' external diameter as. to

snugly fit in .cyli'ndenl Bvir'i order :to properly. guide thewlower enduo-f cylinderflf-i Tliisjsleevetiis pro.-

vided= with a plurality of Icircumirentially spaced openings 4 8101- pl acii'lg chamben LGin communieation with; thednterior-of cylinderbelow the sleeve, 7 v I Y flhe -up persend of cylinder .93 carries. bearing sleeve l9 andt 28{ between-. which; is interposed suitablerannular. packing means. 2| to, pr evnt fluid-fromleaking masttliertwo cylindrs'fyetlpermi-tting'the cylindersatohavezrelative laig ial 11lovememit. Thev bearing sleeveseand packing, .means are-held inn-positionaby a retaining can l z secured wth rupper.endwoflcylinderasL 4 I i v Withimcylinder B- isra special-piston construe; hon- 23.- -dividing--thezspace within the .two. ,eylin ders inte' .uppenohambeiz Aand alqwepcham ber? B the former-being solely-within cylinder 8' and "the -latter within :the lower .part ofs cylinder 8 andnthe cylinder Bgsaid: chamber B also in cluding chambenl fi betweem the walls oi thgcylind'ersi; GhambervzBlis:filledwitl non'econipressie ble fluid such. asaoil orihydraulioubrakelfluidand chambemAt is r filled; with acompressible fluid vor,

gas; preferably air, underpressurevacl niitted-Iv into: chamber Ar through an: -inletw 34 in can lfllr whiclr is: 1 Controlled Lbyy any air pressuiie checki Waiver-2 5.: v The: noncompvessiblerr fluid ais admittedztbflchamberiBthrough a passagali in capyl zwvhen the closurerplug zlisere'moved When the chambersi'A-Y-and; Bi are :filledwwith fluid Fwithcthe air im:chamben-A undenpressure, theyieldablelsdeviceeorrstrutv willi ibe in :operative condition-r4. Uiidei:itliesetconditionsxthe pnessures imboth: chamber are tne same-zamthez-pistonl c'on= struction onlyactsas aanovableiseparatmgwait As the device operates when the vehicle moves, cylinders 8 and 9 will move relatively to each other both in an inward and an outward direction. As cylinder 8 moves inwardly with respect to cylinder 9, piston construction 23 will be forced upwardly, thus placing the air in chamber A under additional pressure since the volume thereof will be'decreased. When cylinder 8 moves outwardly :with respect to cylinder 9, piston construction 23 will move downwardly with respect to cylinder 9 and the volume of chamber A will 7 increase. Since the air in chamber A is compressible, it will act as a cushioning means between the wheel and the frame of the vehicle and thus absorb road shocks.

When a piston of the ordinary type. that is, one with a solid head, is employed, it will move relatively to the cylinder 8 each time there is an increase or a decrease in the force acting on the strut. Since a large majority of the changes in forcesacting on the strut will be small due to the wheel moving over a fairly even roadway movement of the packing means for the partition each time there are small changes in forces acting on the device or strut, thus preventing considerable wear and yet at the same time the air in chamber A and the liquid in chamber B will always be equalized. As shown in-Figure 4,

my improved piston construction comprises a diaphragm 28 made of a flexible material such as rubber, synthetic rubber or the like and extending across cylinder 8.2 The peripheral portion of the diaphragm is formed with oppositely extending annular lips 29 and 30 for cooperation with the cylinder wall,-'lip 29 being exposed to the pressure of the liquid in chamber B and lip 30 being exposed to the air under pressure in chamber A, thus maintaining said lips in pressure contact with the cylinder wall. The central part of the diaphragm has a hub-like portion 3| for receiving a pin 32 and sealing it thereto.

Positioned on opposite sides of the diaphragm are two cup-shaped members 33 and 34 held in clamped relation to the hub of the diaphragm by a shoulder 35 at one end of the pin and a nut 36 at the other end of said pin. The members 33 and 34 have a loose fit in the cylinder and each is so shaped that the peripheral portions thereof are spaced from the peripheral portion of the diaphragm, thus permitting the members to have relative movement with respect to the peripheral portion of the diaphragm before mak'-, ing any contact therewith. The member 33 is provided with perforations 31 in order that the liquid in chamber B may contact the diaphragm l at all times and member 34 has perforations 38 in order that the air under pressure in chamber A may contact the diaphragm on the opposite side of the liquid at all times.

With a piston construction as described it is seen that if cylinder 8 moves slightly downwardly with respect to cylinder 9, the diaphragm can flex upwardly over its central portion to maintain the pressures in chambers Aand B, equal inder may assume.

and without any relative movement between the sealing lips of the diaphragm and the wall of cylinder 8. Similarly, when cylinder 8 has a slight upward movement, the central portion of the diaphragm can flex downwardly to maintain the pressures in the two'chambers equal without any movement of the'sealing lips relatively to the cylinder wall. However, in the event there tain the liquid in chamber B and the air in chamber A equalized, then the peripheral portion of one of the. cup-shaped members 33 or 34 will engage the peripheral portion of the diaphragm and move it bodily relatively -to the cylinder wall and the piston construction will then act as an ordinary piston with sealing cups at its periphery.

In order to decrease the friction between the diaphragm and the wall of the cylinder, the peripheral portion of the diaphragm between lips 29 and 30 has imbedded therein an annular ring 39 of some suitable bearing material having a less coefiicient of friction with the cylinder wall than the material of the diaphragm. This ring is provided with an annular groove 40 which communicates with a radial passageway M in the diaphragm leading to an axial passage 42 in the hub pin 32. This latter'pass'age 'in. turn communicates with a tube 43 which is connected to the end of the pin and extends downwardly through chamber B and telescopes with a hollow pin 44 extending upwardly into chamber B fromv the bottom of cylinder 9. A passage lfi places this hollow pin in constant communication with the atmosphere. By means of this construction'it is seen that the annular groove 40 at the rear of the sealing lips 29 and 39 is at all times'in communication with the atmosphere regardless of the relative positions the, diaphragm and .cyl-

By maintaining the. rear of the lips of the cups at atmospheric pressure there would be no possibility of a back pressure being built up behind the lips which would tend to break the sealing action of the lips. Thus it is seen that if there should be some leakage of air past the sealing lip 30, this leakage will not decrease the pressure acting on the lip to maintain it in pressure contact with the'cylinder wall 8 since the air under pressure which leaks by the lip immediately assumes atmospheric pressure as soon as it reaches the annular groove.

Pin 44, into which the tube 43 telescopes, forms a part of a means for controlling the flow of fluid between the two cylinder portions of chamber B and prevents too rapid build up of pressure in the portionof chamber B at the bottom of the piston construction 23. It is desired to control-the flow of fluid between these two cylinders when'a considerable force acts on the device to move the cylinders toward each other, as, forexample, when the entire weight of the'vehicle comes down upon a device when a large obstruction is encountered or when the vehicle goes over an embankment.

The pin 46 is provided'with angexternalconical' surface and extends through an opening 46in a wall '47 secured to the lower end'ofcylinder, 8

rate of" flow, thedownward movement: oi cylin dena will-be slowed up or checked? The/large force acting to move the cylinders toward each other will thus notbecome eflective suddenly on the'piston and air chamber A. The shock is'thus ment of cylindersv 8 and 9, the ring will seat on i top of sleeve IT and all fluid mustflow through these two openings. The ring will have noefiect inecontrolling the flow of fluid throughwpassages lfl when cylinder 8'.movesinwardly with respect to cylinder 9 since-under these conditions the fluid flowing through passages l8-wil1 lift the ring on sleeve i1 and flow around the ring. The ring in Figure 2 is shown in an unseated position and engaged with,a shoulder 50 for limiting its unseating movement.

Being aware of the possibility of modifications in the particular structure herein described without departing from the fundamental principles of my invention, I do not intend that its scope be limited except as set forth by the appended claims. v

Having fully described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. In a device of the class described having a cylinder, a piston construction mounted therein forming separated chambers and fluid normally under equal pressures in said chambers, said piston construction comprising a flexible diaphragm extending across the cylinder and having its peripheral portion in pressure contact with the cylinder wall, and rigid means carried by the central portion of the diaphragm and positioned on opposite sides thereof, said rigid means having peripheral portions spaced apart a greater distance than the axial thickness of the peripheral portion of the diaphragm whereby when there are small momentary changes in pressure of the fluid in one of the cylinders limited flexing of the central portion only of the diaphragm will be present and when there are larger changes in pressure the entire diaphragm will be moved as a result of engagement of the peripheral portion of the diaphragm by a peripheral portion of said means.

2. In a device of the class described having a cylinder, a piston construction mounted therein forming separated chambers and fluid normally under equal pressures in said chambers, said piston construction comprising a flexible diaphragm adjacent its central portion for movement with mg sealing-dips::he'ld'fimpressura contactswithzthe cylinder wallbyitheifluidipressuress memberszcam riedon-opposite sidesJbfithedi'aphragm andzsc associated with i the diaphragm-1 as: to: permitctlie central part 1. of? thediaphragm u have limited flexing-in opposite axial. directions! relatively-to itslperipheral portion when; there; are limited changes inzpressures of; the fluids: but? causing said'i diaphragm togmove. bodily relativelyyto the cylinder wall. whenv the: a change in. pressure a is 'greaterthan that necessary to 'flexthediaphra'gm to itsjimit asldeterminedby azmemben'.

4: Ida device-oflithe class.described..having:;a,.

cylinder; a piston constructionr'mounted;therein f arming." separated Ii chambers: and: fi'uid I normally under: equal pressureszinsaid:chambersgsaidypise ton constru'ctioncomprising. a: flexible diaphragm extending; across the cylinder: and having: its

peripheral portionzprovided with; outwardly ex-+ tending: sealingzlips heldm pressure contact-with the: cylinder wall. by the-fluid pressures,-. means for limiting the flexing of the central portion of the diaphragm relatively to its'peripheral por- -tion when there is a change in the fluid pressures, and means for maintaining the rear portion of each lip subject to atmospheric pressure.

5. In a device of the class described having a cylinder, a piston constructionmounted therein forming separated chambers and a fluid normally underv pressure in each chamber, said piston construction comprising a flexible member extending across the cylinder and having its peripheral portion in sliding pressure contact with v the wall of the cylinder, and rigid members secured to opposite-sides of the flexible member said central portion and being spaced from the peripheral portion for engagement therewith extending across the cylinder and having its peripheral portion provided with outwardly extending sealing lips held in pressure contact with the cylinder wall by the fluid pressures, and means for limiting the flexing of the central portion of the diaphragm relatively to its peripheral portion when there is a change in the fluid pressures.

3. In a device of the class described having a cylinder, a piston construction mounted therein forming separated chambers and fluid normally under equal pressures in said chambers, said piston construction comprising a flexible diaphragm extending across the cylinder and having its peripheral portion provided with outwardly extendwhen a predetermined flexing of the central portion of said flexible member takes place on either side of its normal plane. 6. In a device of the class described having a cylinder, a piston construction mounted therein forming separated chambers and a fluid normally under pressure in each chamber, said piston construction'comprising a flexible member extending across the cylinder and having its peripheral portion provided with annular lips extending outwardly on opposite sides thereof and maintained in pressure contactwith the cylinder wall by fluid pressure in the chambers, and members secured to the central portion only of the flexible member and positioned on opposite sides thereof, said members having a sliding fit in the cylinder and being so spaced from the flexible member between the central portion and the periphery thereof that the central portion of the flexible member can have a predetermined relative movement with respect to its peripheral portion and on either side of anormal plane of the flexible member.

'7. In a .yieldable device of th class described, two relatively movable telescoping cylinders having their outer ends closed, a. piston construction mounted in one of the cylinders and dividing the cylinders into twochambers, a non-compressible fluid in one chamber and a compressible fluid under pressure in the other chamber, said piston construction comprising a diaphragm having a peripheral portion provided with oppositely extending sealing lips engaging the cylinder wall,

means carried by the diaphragm for causing it mined flexing of its centralportion, means estab-' lishing an annular space between the lips, and

1 means comprising conduit means extending through the diaphragm for placingthe space in communication with the atmosphere at all times.

.8. In a yieldable device of the class described, two relatively movable telescoping cylinders having their outer ends closed, a piston construction mounted in one ofthe cylinders and dividing the cylinders into two chambers, a non-compressible peripheral portion provided with oppositely exwall when the diaphragm is moved by a difierential pressure resulting from relativemovement of 2 0 posite sidesof the diaphragm.

the cylinder but only after. a predetermined flexing of its central portion, means establishing an 10 fluid in one chamber and a compressible fluid 1 under pressure in the other chamber, said piston construction comprising a diaphragm having a annular space between the lips, an axially extending tube" carried by the piston construction,

means connecting said tube to atmosphere but' permitting movement of the piston construction, and means for placing the tube in connection with said annular space between the lips.

9,. In a device of the class described having a cylinder, piston construction mounted therein forming separated chambers andfluid normally under equal pressures in said chambers, said piston construction comprising a flexible diaphragm directly subject on opposite sides thereof to the fluid. pressures in said chambers and extending across the cylinder with its peripheral portion in pressure contact with the cylinder wall, and means associatedwith the diaphragm for limiting flexing of the central part of the diaphragm relatively to its peripheral portion and the cylinder wall when differential pressures act on op- STEVE SCHNELL. 

